Mounting structure of electronic component and method of manufacturing electronic component

ABSTRACT

A mounting structure includes: an electronic component including: a functional element having a predetermined function; a first resin protrusion section having a surface covered by a covering film including a conductive section electrically connected to the functional element; and a second resin protrusion section that is disposed inside an area surrounded by the first resin protrusion section, and has adhesiveness at least on a surface of the second resin protrusion section, and a base member having a connection electrode and adapted to mount the electronic component. In the structure, the second resin protrusion section mounts the electronic component on the base member in a condition in which the conductive section of the covering film has conductive contact with the connection electrode due to elastic deformation of the first resin protrusion section.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a continuation application of U.S. application Ser. No.12/561,287 filed Sep. 17, 2009, which claims priority to Japanese PatentApplication No. 2008-247495, filed Sep. 26, 2008 which is expresslyincorporated by reference herein in its entirety.

BACKGROUND

1. Technical Field

The present invention relates to a mounting structure of an electroniccomponent, and a method of manufacturing an electronic component.

2. Related Art

An electronic component such as a quartz crystal resonator including afunctional element is fixed in the state in which excitation electrodesprovided to the quartz crystal resonator and connection electrodes forconnecting the quartz crystal resonator to a drive circuit haveconductive contact with each other via a conductive paste such as asolder paste (see, e.g., JP-A-11-261360). In the case of using such aconductive paste, the connecting section between the quartz crystalresonator and each of the connection electrodes might be damaged when animpact such as a drop impact is applied thereto, which is a factor fordegrading connection reliability.

Therefore, it is possible to adopt a mounting structure of an electroniccomponent in which a bump electrode composed of a core section havingelasticity and a conductive film disposed on the surface of the coresection is provided to the excitation electrode, and the bump electrodeand the connection electrode have conductive contact with each other viaan adhesive. However, in the case of adopting such a bump electrode,outgas generated from the adhesive might change the vibrationcharacteristic of the quartz crystal resonator, thereby degrading thereliability.

SUMMARY

An advantage of the invention is to provide a mounting structure of anelectronic component and a method of manufacturing an electroniccomponent capable of preventing degradation of electronic componentcharacteristic by preventing influence of the outgas.

According to a first aspect of the invention, a mounting structureincludes: an electronic component including: a functional element havinga predetermined function; a first resin protrusion section having asurface covered by a covering film including a conductive sectionelectrically connected to the functional element; and a second resinprotrusion section that is disposed inside an area surrounded by thefirst resin protrusion section, and has adhesiveness at least on asurface of the second resin protrusion section, and a base member havinga connection electrode and adapted to mount the electronic component. Inthe structure, the second resin protrusion section mounts the electroniccomponent on the base member in a condition in which the conductivesection of the covering film has conductive contact with the connectionelectrode due to elastic deformation of the first resin protrusionsection.

According to the mounting structure of an electronic component of thefirst aspect of the invention, there can be obtained a structure inwhich the first resin protrusion section covered by the covering film isused as the electrical contact and the second resin protrusion sectionis made to function as the bonding material, thereby mounting theelectronic component on the base member while keeping the preferableconducting state. Here, since the first resin protrusion section iscovered by the covering film, the influence of the outgas generated fromthe resin can be prevented. Further, since the second resin protrusionsection is surrounded by the first resin protrusion section in theperiphery thereof, thereby being put into the sealed condition. Thus,the influence of the outgas generated from the second resin protrusionsection can be prevented. Therefore, degradation of the characteristicof the electronic component due to the outgas can be prevented. Further,since both of the first and second resin protrusion sections haveelasticity, the load to the conducting section can be reduced even inthe case in which an external impact is applied, thus superiorconducting reliability can be obtained.

Further, in the mounting structure of an electronic component of thefirst aspect of the invention, it is preferable that the functionalelement be a quartz crystal element.

In the first aspect of the invention, the electronic componentconfigures the quartz crystal resonator provided with the quartz crystalelement. Therefore, the deterioration of the vibration characteristic ofthe quartz crystal resonator due to the outgas can be prevented asdescribed above, and the quartz crystal resonator provided with highconducting reliability can be obtained.

Further, in the mounting structure of an electronic component of theabove aspect of the invention, it is preferable that the first resinprotrusion section and the second resin protrusion section be made of asame photosensitive resin material.

According to this configuration, it becomes possible to simultaneouslyform the first and second resin protrusion sections using, for example,a photolithographic process. Therefore, the manufacturing process of theelectronic component can be simplified, and the manufacturing cost canbe reduced.

Further, in the mounting structure of an electronic component of thefirst aspect of the invention, it is preferable that a height of thesecond resin protrusion section be smaller than a height of the firstresin protrusion section.

According to this configuration, the first resin protrusion section isdeformed elastically to make the conducting section and the connectionelectrode adhere tightly to each other, thereby putting the second resinprotrusion section into the sealed condition in a reliable manner.

Further, in the mounting structure of an electronic component of thefirst aspect of the invention, it is preferable that the second resinprotrusion section have a cross-sectional shape having a width smallerthan a width of a cross-sectional shape of the first resin protrusionsection.

In the case in which, for example, the first and second resin protrusionsections are formed by applying a liquid resin material using a spincoat process, patterning it, and then melting the resin, by setting thewidth of the protrusion section in the cross-sectional shape to berelatively large, the height of the protrusion section can be formed tohave a relatively large height. Therefore, the second resin protrusionsection described above can be formed to have a height smaller than theheight of the first resin protrusion section.

Further, in the mounting structure of an electronic component of thefirst aspect of the invention, it is preferable that the covering filmbe formed of an electrode layer provided to the functional element.

According to this configuration, the covering film can be formedtogether with the electrode layer in the manufacturing process of theelectronic component, thus the manufacturing process can be simplified.

According to a second aspect of the invention, there is provided amethod of manufacturing an electronic component that is mounted on abase member having a connection electrode, and includes: a functionalelement having a predetermined function; a first resin protrusionsection formed on the functional element; a second resin protrusionsection that is formed inside an area surrounded by the first resinprotrusion section, made of a same material as a material of the firstresin protrusion section, and has a bonding function; and a coveringfilm including a conductive section electrically connected to thefunctional element and covers a surface of the first resin protrusionsection. The method includes a step for applying a resin material havinga function of a bonding material on the functional element; a step forforming a first resin pattern to configure the first resin protrusionsection, and a second resin pattern, inside an area surrounded by thefirst resin pattern, to have a width smaller than a width of the firstresin pattern to configure the second resin protrusion section bypatterning the resin material; a step for forming the second resinprotrusion section to have a height smaller than a height of the firstresin protrusion section by melting the first resin pattern and thesecond resin pattern; and a step for forming the covering film to coverthe first resin protrusion section.

When mounting the electronic component obtained by the manufacturingmethod according to the second aspect of the invention on the basemember, the influence of the outgas can be prevented by the first resinprotrusion section with the surface covered by the covering film and thefact that it is surrounded by the first resin protrusion section in theperiphery. Since the electronic component has the second resinprotrusion section surrounded by the first resin protrusion section inthe periphery thereof, the second resin protrusion section can reliablybe put into the sealed condition by elastically deforming the firstresin protrusion section, thus the influence of the outgas generatedfrom the second resin protrusion section can reliably be prevented. Asdescribed above, the electronic component with the degradation of thecharacteristic due to the outgas prevented can be manufactured.

Further, in the method of manufacturing an electronic component of thesecond aspect of the invention, it is preferable that the step offorming, on the functional element, an electrode layer to beelectrically connected to the functional element be further provided,and the covering film is formed of a part of the electrode layer.

According to this configuration, the covering film can be formedtogether with the electrode layer, thus the manufacturing process of theelectronic component can be simplified.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described with reference to the accompanyingdrawings, wherein like numbers reference like elements.

FIG. 1 is a diagram showing a cross-sectional configuration of a quartzcrystal resonator package.

FIG. 2 is a plan view of the quartz crystal resonator package shown inFIG. 1.

FIG. 3 is a bottom view of the quartz crystal resonator.

FIGS. 4A and 4B are diagrams each showing a cross-sectionalconfiguration along the A-A′ arrowed line shown in FIG. 3.

FIGS. 5A through 5D are diagrams showing a process of forming bumpelectrode and a bonding section.

FIGS. 6A and 6B are diagrams for explaining a method of mounting thequartz crystal resonator.

DESCRIPTION OF AN EXEMPLARY EMBODIMENT

An embodiment of the invention will hereinafter be explained withreference to the drawings. It should be noted that the scale size ofeach member is accordingly altered so that the member is shown largeenough to be recognized in the drawings used in the followingexplanations.

FIG. 1 is a diagram showing a quartz crystal resonator package adoptinga mounting structure of an electronic component according to the presentembodiment of the invention. FIG. 1 is a diagram showing across-sectional configuration of the quartz crystal resonator package,FIG. 2 is a plan view corresponding to FIG. 1, and FIG. 3 is a bottomview of the quartz crystal resonator. Further, FIGS. 4A and 4B arecross-sectional configuration diagrams corresponding to the view alongthe A-A′ line shown in FIG. 3, and are diagrams for explaining a shapeof a resin protrusion.

The quartz crystal resonator package (the mounting structure of anelectronic component) 2 is provided with a quartz crystal resonator (anelectronic component) 1, and a container (a base member) 3 forencapsulating the quartz crystal resonator 1. The quartz crystalresonator 1 is provided with a quartz crystal element (a functionalelement) 11, a pair of excitation electrodes 12, 13, bump electrodes 14,and bonding sections 15 as shown in FIGS. 1 through 3.

The container 3 is provided with connection electrodes 33, 34 used forelectrical connection to the quartz crystal resonator 1 as describedlater in detail, and terminal electrodes 35, 36 used when being mountedon a circuit board (not shown) or the like.

The quartz crystal element 11 is a plate like member having asubstantially U shape in plan view, and a planar shape like a tuningfork having two arm sections 22, 23 extending in parallel to each otherin the same directions from a base section 21.

Each of the pair of excitation electrodes 12, 13 is formed of aconductive material such as aluminum (Al) or gold (Au) on one surface ofthe quartz crystal element 11. Further, the excitation electrode 12 isformed on the one surface of the quartz crystal element 11 so as toextend from the base section 21 to the arm section 22. Further, theexcitation electrode 13 is formed on the one surface of the quartzcrystal element 11 so as to extend from the base section 21 to the armsection 23.

The bump electrode 14 is formed on one surface of the base section 21 inthe condition of being electrically connected to the excitationelectrodes 12, 13 described above. The bump electrode 14 is providedwith resin core sections (first resin protrusion sections) 24 eachshaped like a protrusion, and a pair of conductive films (coveringfilms) 25, 26 formed respectively on the surfaces of the resin coresections 24 as shown in FIGS. 1 and 3.

The conductive films 25, 26 are formed by patterning films formed by,for example, a sputtering process. In the present embodiment, theconductive films 25, 26 are formed continuously to the excitationelectrodes 12, 13 by patterning an Au/Cr layer formed by a sputteringprocess, and therefore, are provided with electrical conduction to theexcitation electrodes 12, 13, respectively. In other words, the quartzcrystal resonator package 2 uses the bump electrodes 14 as theelectrical contacts between the quartz crystal resonator 1 and thecontainer 3.

It should be noted that the conductive films 25, 26 can be made of metalor an alloy such as gold (Au), titanium tungsten (TiW), copper (Cu),chromium (Cr), nickel (Ni), titanium (Ti), tungsten (W), nickel vanadium(NiV), aluminum (Al), palladium (Pd), or a lead-free solder, and formedof a single layer or multiple layers of any of these materials.

As shown in FIG. 2, the resin core sections 24 are each configured tohave a substantially annulus ring shape in the plan view, and theconductive films 25, 26 covering the resin cores 24 are each formed tohave an annulus shape. Further, the resin core sections 24 are eachformed to have a substantially semicircular cross-sectional shape bypatterning a resin material by a photolithographic process or an etchingprocess as described later and then melting the resin pattern.

Since the resin core sections 24 are covered by the conductive films 25,26 as described above, various kinds of resin materials can be used asthe resin core sections 24, and the resin core sections 24 are made ofphotosensitive insulating resin or thermoset insulating resin such aspolyimide resin, acrylic resin, phenol resin, silicone resin,silicone-modified polyimide resin, or epoxy resin (epoxy resin is usedin the present embodiment).

Further, inside an area of the one surface of the base section 21surrounded by the resin core section 24 (the bump electrode 14), thereis disposed the bonding section (a second resin protrusion section) 15shaped like a protrusion. As shown in FIG. 1, the bonding sections 15are arranged so that the resin core sections 24 forming the bumpelectrodes 14 deform elastically along the surface shapes of theconnection electrodes 33, 34 described later, respectively, thus thequartz crystal resonator 1 can be mounted of the container main body 31in the condition in which the conductive films 25, 26 have conductivecontact with the connection electrodes 33, 34, respectively. The quartzcrystal resonator 1 has a cantilever structure in which the base section21 is supported by the container 3 as shown in FIG. 1.

As the bonding section 15, various kinds of materials can be usedproviding the materials have adhesiveness at least on the surfacesthereof, and specifically in the present embodiment, the bonding section15 is made of the same material (epoxy resin) as that of the resin coresection 24 described above. By thus forming the resin core section 24and the bonding section 15 from the same material, the photolithographicprocess and the etching process can be executed in the same conditions,thus the manufacturing process can be simplified. It should be notedthat the bonding section 15 can also be configured by separately formingan adhesive layer having adhesiveness on the surface of resin, whichdoes not function as a bonding material.

As shown in FIG. 4A, the height h1 of the bonding section 15 is set tobe lower than the height h2 of the resin core section 24. Thus, theresin core sections 24 are deformed elastically as described abovethereby making the conductive films 25, 26 and the connection electrodes33, 34 adhere tightly to each other, respectively, and thus the bondingsection 15 can reliably be put into a sealed condition.

Further, as shown in FIG. 4B, the width B of the bonding section 15 inthe cross-sectional shape is set to be smaller than the width A of theresin core section 24 in the cross-sectional shape. By designing thewidth B of the bonding section 15 to be small as described above, theshape having the height h1 of the bonding section 15 lower than theheight h2 of the resin core section 24 can easily be obtained in themanufacturing process described later.

The container 3 described above is provided with the container main body31 and a lid member 32 for covering the container main body 31.

The container main body 31 is formed to have a substantially box-likeshape, and is formed of an insulating material such as ceramics.Further, on the upper surface of the bottom section of the containermain body 31, there are formed the connection electrodes 33, 34.Further, on the lower surface of the bottom section of the containermain body 31, there are formed the terminal electrodes 35, 36 used whenit is mounted on a circuit board (not shown).

The connection electrodes 33, 34 are each formed by stacking a layer ofan Au film on a plated layer of Ni formed on a W film, and connectedrespectively to the terminal electrodes 35, 36 via the wiring (notshown) formed on the container main body 31.

Similarly to the container main body 31, the lid member 32 is made of aninsulating material such as ceramics. Further, the lid member 32 isbonded to the opening section of the container main body 31 by, forexample, brazing, thereby encapsulating the quartz crystal resonator 1inside the space formed between the lid member 32 and the container mainbody 31.

As described above, the quartz crystal resonator package 2 according tothe present embodiment uses the bump electrodes 14 as the electricalcontacts, thereby making it possible to mount the quartz crystalresonator 1 on the container 3 while keeping the preferable conductingstate by the bonding sections 15. Since the resin core sections 24 arecovered respectively by the conductive films 25, 26, the problem thatthe outgas generated from the resin core sections 24 deteriorates thevibration characteristic of the quartz crystal resonator 1 (the quartzcrystal element 11) can be prevented. Further, since the resin coresections 24 are elastically deformed along the surface shapes of theconnection electrodes 33, 34 as shown in FIG. 1, the bonding sections 15become in the state of adhering tightly to the conductive films 25, 26,respectively. In other words, the bonding section 15 is put into thesealed state by being surrounded by the bump electrode 14 in theperiphery thereof. Thus, the problem that the outgas generated from thebonding section 15 deteriorates the vibration characteristic of thequartz crystal resonator 1 (the quartz crystal element 11) can beprevented.

As described above, according to the quartz crystal resonator package 2according to the present embodiment, the deterioration of thecharacteristic of the quartz crystal resonator 1 (the electroniccomponent) due to the outgas generated from the resin material can beprevented, thereby providing the component with high reliability.Further, since the resin core sections 24 and the bonding sections 15are both provided with elasticity, the load to the conducting sectionbetween the bump electrodes 14 and the connection electrodes 33, 34 canbe reduced even in the case in which an external impact is appliedthereto, thus superior conduction reliability can be obtained. Further,since the bump electrodes can be manufactured using thephotolithographic process, downsizing of the electrode can be achievedcompared to the conductive paste of the related art.

As an embodiment of an aspect of the invention related to a method ofmanufacturing an electronic component, a process of manufacturing thequartz crystal resonator package 2 (the quartz crystal resonator 1)described above will be explained. In the present embodiment, there arecharacterizing features in the processes of forming the bump electrodes14 and the bonding sections 15 described above. Therefore, theexplanations will hereinafter be presented with a focus on the method ofmanufacturing the bump electrodes 14 and the bonding sections 15.

Firstly, as shown in FIG. 5A, a photosensitive resin material 50 isapplied on one surface of the quartz crystal element 11 by a spin coatmethod. Specifically, in the present embodiment, epoxy resin having afunction as the bonding material in the bonding process described lateris applied.

Subsequently, exposure and development process is executed.Specifically, as shown in FIG. 5B, a photomask M provided with openingscorresponding to a first resin pattern P1 forming the resin coresections 24 described above and a second resin pattern P2 forming thebonding sections 15 described above is used. The photomask M is arrangedto have a width of a first opening section H1 corresponding to the firstresin pattern P1 larger than the width of an opening section H2corresponding to the second resin pattern P2. It should be noted thatthe second opening section H2 is disposed inside the area surrounded bythe first opening section H1.

By executing the exposure process and the development process using sucha photomask M, the first resin pattern P1 and the second resin patternP2 are formed on the quartz crystal element 11 as shown in FIG. 5C. Thewidth H11 of the first resin pattern P1 in the cross-sectional shape isarranged to be larger than the width H12 of the second resin pattern P2in the cross-sectional shape.

As described above, in the present embodiment, by forming the first andsecond resin patterns P1, P2 from the same photosensitive resinmaterial, it becomes possible to form the first and second resinpatterns P1, P2 in the same photolithographic process. Thus, it becomespossible to achieve simplification of the manufacturing process.Further, since the first and second resin patterns P1, P2 are formedusing the photolithographic process, a fine pattern can be formed.

Subsequently, as shown in FIG. 5D, by heating the first and second resinpatterns P1, P2, the first and second resin patterns P1, P2 are melted,thereby forming the resin core sections 24 and the bonding sections 15having the semicircular shapes. As the heating method, various methodscan be cited, and in the present embodiment, the heating process isperformed by putting the quartz crystal resonator 1 in a heating oven,for example.

In this case, as the first and second resin patterns P1, P2 are melted,the height of the second resin pattern P2 with the smaller width H12becomes smaller than that of the first resin pattern P1 with the largerwidth H11. Thus, the resin core sections 24 and the bonding sections 15with the height smaller than that of the resin core section 24 areformed on the quartz crystal element 11.

After forming the resin core sections 24 and the bonding sections 15 inthe manner as described above, the excitation electrodes 12, 13 areformed on the quartz crystal element 11. The excitation electrodes 12,13 are formed by depositing the Au/Cr layer using, for example, asputtering process, and then patterning the Au/Cr layer to form adesired pattern. Specifically, the Au/Cr layer is patterned so as toform a covering state of the resin core sections 24 and to expose thebonding sections 15. Thus, the excitation electrodes 12, 13 and theconductive films 25, 26 covering the resin core sections 24 can beformed. As described above, in the present embodiment, the conductivefilms 25, 26 are formed with parts of the excitation electrodes 12, 13,respectively, thus the manufacturing process can be simplified.

Through the process described above, the quartz crystal resonator 1provided with the resin core sections 24 and the bonding sections 15 atthe connection sections of the excitation electrodes 12, 13 can bemanufactured.

Then, a method of mounting the quartz crystal resonator 1 will beexplained with reference to FIGS. 6A and 6B. Here, FIGS. 6A and 6B arecross-sectional views showing the bump electrode 14 when mounting thequartz crystal resonator 1 on the container 3.

Firstly, the bump electrodes 14 and the bonding sections 15 provided tothe quartz crystal resonator 1 are contacted and pressed against theconnection electrodes 33, 34 provided to the container main body 31 (seeFIGS. 6A and 6B). It should be noted that the mounting process of thequartz crystal resonator 1 is executed in a heated condition.

In this case, the resin core sections 24 are deformed elastically alongthe shape of the connection electrodes 33, 34, respectively.

Then, the conductive film 25 is deformed along the surface shape of theconnection electrode 33 in association with the elastic deformation ofthe resin core section 24, and at the same time, the conductive film 26is deformed along the surface shape of the connection electrode 34.Thus, conductive contact with sufficient contact area is obtainedbetween the conductive film 25 and the connection electrode 33, andbetween the conductive film 26 and the connection electrode 34. Further,the bonding sections 15 with the height smaller than that of the resincore section 24 come in contact with the connection electrodes 33, 34,respectively. Then the bonding sections 15 are cured.

Therefore, the bonding sections 15 can bond the bump electrodes 14 andthe respective connection electrodes 33, 34 due to the elasticdeformation of the resin core sections 24, thereby keeping the contactcondition between the conductive film 25 and the connection electrode33, and between the conductive film 26 and the connection electrode 34.

In the manner as described above, the quartz crystal resonator 1 ismounted inside the container main body 31. Subsequently, the containermain body 31 and the lid section 32 are bonded to each other, therebyencapsulating the quartz crystal resonator 1. The quartz crystalresonator package 2 is formed in the manner as described above.

In this case, since the resin core sections 24 are covered respectivelyby the conductive films 25, 26, it can be prevented that the outgasgenerated from the resin core sections 24 deteriorates the vibrationcharacteristic of the quartz crystal resonator 1 (the quartz crystalelement 11). Further, the bonding sections 15 are surrounded by therespective bump electrodes 14 in the periphery thereof so as to be keptin the sealed condition as shown in FIG. 6B, and therefore, it can beprevented that the outgas generated from the bonding section 15deteriorates the vibration characteristic of the quartz crystalresonator 1 (the quartz crystal element 11).

According to the quartz crystal resonator package 2 thus formed, thedeterioration of the characteristic of the quartz crystal resonator 1due to the outgas generated from the resin material is prevented,thereby obtaining high reliability.

Further, in the case in which, for example, an impact such as a dropimpact is applied to the correction section between the quartz crystalresonator 1 and the container main body 31, the resin core sections 24is deformed elastically to absorb the impact.

It should be noted that the invention is not limited to the embodimentdescribed above, but various modifications can be executed thereonwithin the scope or the spirit of the invention.

For example, although in the embodiment, the configuration of providinga single bonding section 15 inside the bump electrode 14 having theannulus ring shape in the plan view is adopted, it is also possible toprovide a plurality of bonding sections 15, thereby improving thebonding strength of the quartz crystal resonator to the container mainbody 31. Further, although in the present embodiment, it is assumed thatthe bonding section 15 has a circular shape in the plan view, thebonding section 15 can be formed to have a vaulted shape. The vaultedshape means a columnar shape having a planar inner surface (bottomsurface) having contact with the quartz crystal element 11, and a curvedouter surface not having contact therewith. Specifically, as thesubstantially vaulted shape, the shapes with lateral cross-sectionalshapes of a substantially semicircular shape, a substantiallysemielliptical shape, and a substantially trapezoidal shape can becited.

1. A mounting structure comprising: an electronic component, theelectronic component including: a functional element having apredetermined function; a first resin protrusion section having asurface covered by a covering film including a conductive sectionelectrically connected to the functional element; and a second resinprotrusion section that is disposed inside an area surrounded by thefirst resin protrusion section, and has adhesiveness at least on asurface of the second resin protrusion section, and a base member havinga connection electrode and adapted to mount the electronic component,wherein the second resin protrusion section mounts the electroniccomponent on the base member in a condition in which the conductivesection of the covering film has conductive contact with the connectionelectrode due to elastic deformation of the first resin protrusionsection.